Quick current volts amps query

Fuzz · 27 Oct 2010 at 23:55

So I have an item that is drawing 500w/hrs hr on a 240v system.

Now say I am drawing that through an inverter from a set of 12v 120amp/hr batteries in series to make 48v

4 x 12v in series = 48v = 120amp/hr

500w/hrs on 240v is 2 amp/hrs
But 500w/hrs on 48v is 10 amp/hrs

Am I drawing 10amps @ 500w or 2amps @ 96w :confused:

Figures are rounded slightly before the pedants start

GeX · 27 Oct 2010 at 23:57

nonsense?

P=IV.

Start again.

bigjimmyauk · 28 Oct 2010 at 00:09

it would be 500watts @ 10amphours on 48 volts
don't forget to account for efficiency loss in the inverter do you know how many percent it is

i have no idea where you got 2amp at 96w from lol

bigjimmyauk · 28 Oct 2010 at 00:09

also might want to read this http://www.lunevalley-tcc.co.uk/12 volt to Mains via inverters.htm

Fuzz · 28 Oct 2010 at 00:16

bigjimmyauk said:
i have no idea where you got 2amp at 96w from lol

500w on a 240v system is 2 amps

96watts on a 48v system is 2 amps

It's late / I need sleep / need coffee

bigjimmyauk · 28 Oct 2010 at 00:19

Scubascorpion said:
500w on a 240v system is 2 amps

96watts on a 48v system is 2 amps

It's late / I need sleep / need coffee

oh i see now lol

just be careful and make sure it's a good inverter if it's for 500watts

do you mind if i ask what the item is in question

Fuzz · 28 Oct 2010 at 00:21

The house

500w was just used as a nice round figure, I fully realise I would probably need a 1000w-1500w Inverter for what I'm planning.

I wasn't sure whether it was Watts or Amps that was a constant. Cheers for help